Hypomotor seizuresLiisa Metsähonkala, MD, PhD

Epilepsia-Helsinki

Helsinki University Hospital

Hypomotor seizures

• seizure type seen in infants, small children and nonverbal patients(Duchowny 1992, Acharya et al 1997)

• the essential feature of hypomotor seizures is arrest of behavior

• a special term developed for those situations when it is not possibleto figure out if the arrest of behavior is an indication of• a subjective feeling

• impared awareness

• hypokinesia

Hamer et al 1999: video-EEG verified seizuresemiology in < 3 y olds

Hypomotor seizures

• special features in the very young:

• poor co-operation and verbal ablities and difficulty to test

• maturation of the brain influences the symptom pattern in

young children (Nordli 2013 review)

• simple motor symptoms are typical

• more complex fine motor symptoms appear by age

• some of the lateralizing signs are seen less frequently

Fogarasi et al 2006

Hypomotor seizures

• arrest of behavior is the essential feature but subtle additional

features are seen (apnea, autonomic symptoms, eye deviation, head

movement)

• hypomotor onset maybe followed by motor symptoms

Case Aapo - a boy with szs from age 1 years

• Aapo was born fullterm, normal birth, no perinatal complications

• Aapo has two sisters, his early developmentwas normal, a little slower in comparison to hissisters

• 1. seizure at the age of 1 y• from awake, arrest of behavior, tremor

• after the first seizure the sz situation soon escalated→ clusters of daily seizures• arrest of behavior, smiling, drooling, large pupils• sometimes eye deviation to the right or up, upper

arms may be stiff but not tonic, no consistentasymmetry

Vaca et al 2018

Seizure classification – hypomotor seizures are most often focal seizures

Seizure classification based only on the clinical symptoms

The main feature = arrest of behavior

Long evolving seizures

Subjective symptoms?

Aware/not aware?

?

?

EEG• interictal EEG – normal background, no epileptic activity

• ictal EEG – discharge in the midline Cz,Pz→ spreadingbilaterally, slow discharge R>L

• → Focal onset nonmotor seizures, awareness not known

Clinical onset

Etiology?

• hypomotor seizures are

seen in both benign genetic

epilepsies, severe infantile

encephalopaties and in focal

structural epilepsies

Källén et al 2002

How about Aapo?

• Genetic etiology? • Benign focal epilepsy of infancy?

• normal background• clusters of seizures• normal development and status

• Other genetic?• No gene investigations were

performed

• Structural etiology?• MRI at the age of 1 year 1 month was

considered normal

Treatment and development

• valproate

• valproate + oxcarbazepine

• valproate + clobazame

• valproate +lamotrigine → infrequent seizures

• mild developmental delay, no clear epileptic encephalopathy

• → follow-up, no further investigations

• → a new MRI in the future was planned

If the seizures would have continued as drugresistant ? A surgical candidate? Localization?

• hypomotor seizures are not specificfor a certain lobe

• frequent both in temporal, posteriorand frontal lobe epilepsies (Källen et al 2002, Fogarasi et al 2003, Vendrame et al 2011)

Källén et al 2002

If the seizures would have continued as drugresistant? A surgical candidate? Localization?

• subtle semiological features: • long seizures

• smiling

• drooling, pallor

• subtle eye movements

• no consistent lateralizing signs

• ictal EEG localizing CPmidline, side R>L

How could we proceed?

• →FDG-PET

• →new MRI

• →genetic investigations

• Stereo-EEG?

What happened later?

The etiology is revealed

• Aapos older sister started to haveseizures→ diagnosis of tuberosissclerosis

• also Aapos father was diagnosed withTSC

• re-evaluation of Aapos MRI → onesubependymal nodule, no cleartubers→ TSC diagnosis

New MRI at the age of 6 years: Several small tubers bilaterally

New referral

• frequent drug resistant seizures

• behavioral problems aggravated by AEDs

• mild learning disability

• seizures have similar features as before

• EEG different, LP focus

More information on seizure semiology

• at the age of 6 years

• arrest of behavior, peculiar smileor laughter, eyes wide open, wandering eye movements

• may fall, occasionally rightsidedclonias

• testing: aware in the beginningof the seizure

More detailed information on seizuresemiology

• at the age of 9 years

• describes visual symptoms: bright transparent light in themiddle with spreading dark linesaround

Clinical onset (at 9 years of age)

Deepest hypometabolism in the left parietal tuber

What happened later?

• Sz classification: Focal onset visual aware seizures

• Localization: Interictal and ictal EEG, FDG-PET → L parietal tuber

• Resection of the L P tuber with intraoperative intracranial recording

• Outcome: seizure free for 10 months after which the seizuresreappeared, the visual symptom is a bit different from thepreoperative

• Primary/additional focus on the other side? Complexity typical for TSC?

Conclusions –hypomotor seizures

• children are not small adults• special semiological features

• special features as patients

• hypomotor seizures are seen in several different epilepsytypes and etiologies –not specific

• useful term for the clinical work

• subtle semiological features, EEG and imaging help in localization, genetic studies

• new information by time

Finland won theWorld Ice Hockey Championships

yesterday !!!!!!